2 Before you take
Do not take Trimethoprim tablets and tell your doctor if you:
- are allergic (hypersensitive) to trimethoprim or any of the other ingredients in the tablet (see section 6)
- are pregnant
- have any blood disorder
- have severe kidney disease
- Trimethoprim should not be given to premature babies or babies during the first few weeks of life.
Check with your doctor or pharmacist before taking Trimethoprim tablets if you have:
- kidney disease or are having dialysis treatment
- a deficiency of folic acid (may cause anaemia).
Taking other medicines
Please tell your doctor or pharmacist if you are taking or have recently taken any other medicines, including medicines obtained without a prescription. Especially:
- antibiotics such as rifampicin
- anticoagulants to prevent your blood clotting such as warfarin
- ciclosporin (to prevent rejection after transplantation)
- digoxin (to treat heart conditions)
- phenytoin (to treat epilepsy)
- pyrimethamine (to treat malaria)
- bone marrow depressants.
Pregnancy and breast-feeding
Trimethoprim should not be used in pregnancy.
If you are breast-feeding, ask your doctor or pharmacist for advice before taking this medicine.
If you have been told you have an intolerance to some sugars, contact your doctor before taking this medicine, as it contains a type of sugar called lactose.
If you are having treatment over a long time, your doctor may carry out regular blood tests.
3 How to take
Always take Trimethoprim tablets exactly as your doctor has told you. If you are not sure, check with your doctor or pharmacist.
Swallow the tablets with a glass of water at the same times each day.
- Severe or sudden infections: (e.g. uncomplicated bacterial cystitis in women) treatment will usually be between 3-14 days, according to the type and severity of infection. Your doctor may double your first dose.
- Adults and children over 12 years: 200mg twice a day.
- Children 6-12 years: 100mg twice a day.
- Children under 6 years: Not recommended; a more suitable dosage form should be used in this age group.
- Long-term treatment and prevention therapy:
- Adults and children over 12 years: 100mg at night.
- Children 6-12 years: 50mg at night. The usual dose is around 2mg per kg body weight of the child per day.
Elderly: doses may be reduced in elderly patients, according to kidney function.
If you take more than you should
If you (or someone else) swallow a lot of tablets at the same time, or you think a child may have swallowed any contact your nearest hospital casualty department or tell your doctor immediately.
If you forget to take the tablets
If you forget to take a dose take it as soon as you remember it and then take the next dose at the right time. Do not take a double dose to make up for a forgotten dose.
If you stop taking the tablets
Do not stop taking Trimethoprim tablets because you feel better. Take the tablets for as long as your doctor has told you or your problem may come back.
4 Possible side effects
Like all medicines, Trimethoprim tablets can cause side effects, although not everybody gets them. Please tell your doctor or pharmacist if you notice any of the following effects or any effects not listed.
Contact your doctor at once if you get an allergic reaction such as swelling of the face, lips, tongue or throat, difficulty breathing, shock or collapse. Aseptic meningitis can occur in some patients. This may show as a combination of symptoms such as headache, fever, stiff neck, tiredness, feeling ill and your eyes become very sensitive to bright light.
Tell your doctor if you notice any of the following side effects or notice any other effects not listed:
Blood: altered number and type of certain blood cells. If you get increased bruising, nose bleeds, sore throats or infections you should consult your doctor. Too much potassium in the blood (you may experience muscle cramps or pain, irregular heartbeats, unusual tiredness or weakness).
Stomach: feeling or being sick, sore mouth, discomfort, this is usually mild and disappears after stopping the tablets.
Skin: sensitivity to light, skin rashes which may be itchy, severe skin reactions such as exfoliative dermatitis (itchy, scaly, flaking, swollen skin), erythema multiforme (circular, irregular red patches), Stevens-Johnson syndrome (severe skin rash with flushing, fever, blisters or ulcers) or toxic epidermal necrolysis (severe rash involving reddening, peeling and swelling of the skin that resembles severe burns).
Liver: changes in liver enzymes (seen in tests), jaundice (yellowing of skin or whites of the eyes)
Kidney: increase in blood creatinine and urea levels (seen in tests)
Muscles: muscle pain.
Other: red, swollen tongue, headache.
If you notice any side effects, they get worse or if you notice any not listed, tell your doctor or pharmacist.
5 How to store
Keep out of the reach and sight of children.
Store below 25°C in a dry place.
Do not use Trimethoprim tablets after the expiry date stated on the label/carton/bottle. The expiry date refers to the last day of that month.
Medicines should not be disposed of via wastewater or household waste. Ask your pharmacist how to dispose of medicines no longer required. These measures will help to protect the environment.